Water dispensing toilets have dramatically advanced the technology of human sanitary needs, but nonetheless a major potential problem still exists. Specifically, defecation usage of the toilet can release intense offensive odors, which can not only linger in the generally enclosed bath room but also spread via the airways to and throughout the adjoining rooms.
Exhaust fans are common in modern bath rooms, intended to offer a means for possibly eliminating or minimizing the discomforts of such odors; but such generally offer only marginal relief. Reasons for the limited effectiveness of exhaust fans in removing odors might be due to: the remote spacing between the toilet (close to the floor) and the fan itself (commonly close to or in the room ceiling), allowing the odors to dissipate into the room well before they are drawn away; the need for removing much of the room air then to capture such odors; and the limited air moving capacity of such fans, compared to the room volume.
Chemicals are also used, but such basically only seem to mask the odors, and not remove them from the room air.